The Fixation of Arsenic by the Brain. 



323 



Experiment 4. — 50 grm. of broken-up filter candle were placed into 250 c.c. 

 of saline solution and. - O75 grm. of neosalvarsan added. Further technique 



as in Experiment 1. 

 Result. — 



Gramme of 

 neosalvarsan. 



Moist filter residue after washing, 50 grm contained 



Supernatant fluid after fixation, 250 c.c „ 0'04 



Final washing fluid „ 



Experiment 5. — Kepetition of Experiment 4, but with finest Venetian 

 charcoal instead of Doulton filter. Air was removed from the charcoal by 

 boiling and the use of the vacuum pump — 0'15 grm. of neosalvarsan were 

 added. 



Gramme of 

 neosalvarsan. 



Moist charcoal residue after washing, 50 grm.... contained 0'00l 



Supernatant fluid after 6xation, 250 c.c ,, - ll 



Final washing fluid „ 



Although a certain degree of absorption of the neosalvarsan was observed 

 in the case of charcoal, it was not so great as with liver and brain tissue, and 

 this fact, taken with the absence of fixation by the filter, suggests that the 

 presence of arsenic in the latter after washing was a true combination and 

 not a purely mechanical phenomenon. 



The conclusion may therefore be drawn that the absence of arsenic from 

 the brain after intravenous injection of salvarsan is not due to a lack of 

 affinity between the drug and the brain, but to an inability of the drug to 

 penetrate into the proper brain substance. 



As is well known, arsenic is not usually found in the cerebrospinal 

 fluid after intravenous injections of salvarsan, and this has been suggested as 

 an explanation of the lack of effect of this drug upon certain syphilitic 

 affections of the brain. On other data, however, we have formed the 

 opinion that the inability of ai'senic to penetrate the brain has no relation 

 to its absence from the cerebrospinal fluid, but is due to a peculiarity of the 

 cerebral capillaries. If, however, neosalvarsan is introduced directly into 

 this fluid by lumbar puncture, then, as shown by Wechselmann, marked 

 toxic symptoms appear. 



Experiment 6. To Demonstrate the Toxity of Neosalvarsan to tlie Nervous 

 System. — In a typical experiment two rabbits were used in addition to a 

 control. 



- 05 grm. of neosalvarsan were dissolved in 10 c.c. of saline solution, and 



